Super Mario Galaxy 2 is the second worst selling
3D Mario game

Behind only Sunshine. This makes me sad. Galaxy 2 released when the Wii had sold at least 70 million consoles, yet it was outsold by Galaxy handily which released just a year after launch. 100 million userbase and Galaxy 2 can't beat Galaxy, M64, or 3D Land. Just two million more than Sunshine, which came out on a console which only sold 21.7 million.

Galaxy 2 was the ultimate 3D Mario but it's sales don't reflect that. Maybe that's why Nintendo brought 3D Mario down this road for Wii U. After all, 3D Land has already sold more than Galaxy 2 in less than 2 years since release at over 8 million.

To all those out there that loved Galaxy, but didn't buy the second one, please don't complain about 3D World not being what you want. You didn't buy Galaxy 2, the greatest 3D Mario, so you have no leg to stand on.

if anything, SMG2 showed Nintendo that they don't actually have to TRY any more, and thus, we got lazy uninspired 3D Land---I may not agree with what you have to say, but I will fight to the death for my right to fight you to the death. -Stephen Colbert

So now we all know why Super Mario 3D World was announced for the Wii U instead of Super Mario Galaxy 3. Nintendo saw the "3D" series being a bigger potential seller instead of the "Galaxy" series.---NNID: PoisonShroom